1. Field of the Invention
The present invention is directed generally to an apparatus for producing composite bodies from laminated layers of plastic film and other materials, as well as a process for producing composite bodies made from laminated layers of plastic film and other materials.
2. Description of the Prior Art
There is an increasing interest expressed by various industries, such as for example, apparatus engineering, vehicle and aircraft engineering or safety technology, for high-strength composite bodies both in the form of semi-finished products, e.g., panels, and finished products and components. Panel producers have been engaged in the development of techniques for the manufacture of products capable of withstanding higher mechanical loads without loss of physical integrity. Such developments include the modification of polymer materials by the incorporation of reinforcing materials, e.g., textiles, glass and carbon fibers, and the development of techniques for the production of integrally consolidated panels using orienting measures and strategic layering techniques.
The techniques that have been developed encompass roll-press stretching or the process described in EP-A-0 207 047 which discloses a multiplicity of biaxially stretched films provided with thin, coextruded sealing coatings, which are pressed under conditions of pressure and heat to form a homogeneous panel having any desired thickness. For this purpose, a pile of films are generally laid between two pressing plates and introduced to intermittently operating hydraulic plate presses. Process parameters determining the pressing operation are pressure, temperature and time. The last parameter, time, is generally the significant limiting factor in the manufacture and production of inexpensive composite laminates, expecially in the manufacture of very thick panels, in particular with regard to the required throughout heating of the panels. While continuously operated run-through presses, such as double-belt presses, represent a practicable, time-saving solution, they are nevertheless limited in the thickness of the panel which can be processed on them, i.e., there is an upper limitation on the thickness of the panel that can be processed through continuous run-through presses.
The range of problems and shortcomings described above also applies to the manufacture of rotationally symmetrical molded bodies, e.g., cylindrical pipes or vessels. Such molded bodies are manufactured by winding layers of plastic film on a winding mandrel in accordance with the contours of the desired finished product. Accordingly, in order to achieve adequate bonding, the moldings must be treated in a conditioning oven until the temperature of the layers of film near the core of the molding have reached the sealing temperature for the particular plastic film used. In this respect, there is a risk that the time required could cause thermally induced morphological changes to the materials employed on the layers of film further away from the core, and especially near the surface of the molding.